Titanium single-electron transistor fabricated by electron-beam lithography

A method to fabricate non-superconducting mesoscopic tunnel junctions by oxidation of Ti is presented. The fabrication process uses conventional electron-beam lithography and shadow deposition through an organic resist mask. Superconductivity in Ti is suppressed by performing the deposition under a suitable background pressure. We demonstrate the method by making a single-electron transistor which operated at T < 0.4 K and had a moderate charge noise of 2.5 x 10(-3) e/rootHz at 10 Hz. Based on non-linearities in the current-voltage characteristics at higher voltages, we deduce the oxide barrier height of approximately 110 mV. The non-superconducting Ti junctions can be useful in several applications. (C) 2002 Elsevier Science B.V. All rights reserved.